1. Field of the Invention
The present invention relates to the field of integrated circuit counters. The present invention more specifically relates to the forming of an irreversibly monotonic up-counter.
2. Discussion of the Related Art
Currently, to form monotonic up-counters, fuse elements have to be used, which have the major disadvantage of causing a destructive programming often incompatible with a programming during operation of the integrated circuit containing the fuse element. Another example relates to EPROM or EEPROM memories, the manufacturing of which requires steps not directly compatible with a CMOS technology.
Further, in both cases, the achieved programming state is either erasable (case of EEPROMs) or optically visible, which is prejudicial in security-type applications for which an inviolable count is desired to be available.
An example of application consists of counting the number of events with respect to a limiting event threshold (number of uses of a program or duration of use). In this type of application, it is generally desired to have a counter, each bit of which respectively takes states 0 or 1 in irreversible fashion to provide a binary word representative of the number of events having occurred.